Method of operation for a three-dimensional, wireless network

ABSTRACT

A method of operation for wireless transmission of data to one or more destination devices across a network that includes a plurality of access points disposed about a building, each access point having a first transmission range of maximum bandwidth and a second transmission range of signal interference, the access points being arranged in a topology wherein each access point is spaced-apart from a nearest neighboring access point by a first distance less than the first transmission range. The data is transmitted by a first access point; then it is repeated by a series of additional access points that extends across the topology. Re-transmission of the data occurs in a manner wherein any pair of access points transmitting on the same channel is separated by a distance greater than the second transmission range. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

RELATED APPLICATIONS

This application is a continuation of Ser. No. 10/367,178 filed Feb. 14,2003, which application is related to co-pending application Ser. No.10/367,197, filed Feb. 14, 2003, [entitled, “SELF-CONFIGURING, ADAPTIVE,THREE-DIMENSIONAL, WIRELESS NETWORK”].

FIELD OF THE INVENTION

The present invention relates generally to wireless networks, and moreparticularly to methods and apparatus for configuring, expanding andmaintaining a wireless network for home or office use.

BACKGROUND OF THE INVENTION

In recent years, wireless networks have emerged as flexible andcost-effective alternatives to conventional wired local area networks(LANs). At the office and in the home, people are gravitating toward useof laptops and handheld devices that they can carry with them while theydo their jobs or move from the living room to the bedroom. This has ledindustry manufacturers to view wireless technologies as an attractivealternative to Ethernet-type LANs for home and office consumerelectronics devices, such as laptop computers, Digital Versatile Disk(“DVD”) players, television sets, and other media devices. Furthermore,because wireless networks obviate the need for physical wires, they canbe installed relatively easily.

Wireless communication systems adapted for use in homes and officebuildings typically include an access point coupled to an interactivedata network (e.g., Internet) through a high-speed connection, such as adigital subscriber line (DSL) or cable modem. The access point isusually configured to have sufficient signal strength to transmit datato and receive data from remote terminals or client devices locatedthroughout the building. For example, a portable computer in a house mayinclude a PCMCIA card with a wireless transceiver that allows it toreceive and transmit data via the access point. Data exchanged betweenwireless client devices and access points is generally sent in packetformat. Data packets may carry information such as source address,destination address, synchronization bits, data, error correcting codes,etc.

A variety of wireless communication protocols for transmitting packetsof information between wireless devices and access points have beenadopted throughout the world. For example, in the United States, IEEEspecification 802.11 and the Bluetooth wireless protocol have beenwidely used for industrial applications. IEEE specification 802.11, andIndustrial, Scientific, and Medical (ISM) band networking protocolstypically operate in the 2.4 GHz or 5 GHz frequency bands. In Europe, astandard known as HIPERLAN is widely used. The Wireless AsynchronousTransfer Mode (WATM) standard is another protocol under development.This latter standard defines the format of a transmission frame, withinwhich control and data transfer functions can take place. The format andlength of transmission frames may be fixed or dynamically variable.

Although traditional wireless networks work fairly well for residentialInternet traffic running at data rates below 1 megabit per second(Mbps), transmission of high-bandwidth video programs is moreproblematic due to the much faster video data rates. High-bandwidth datatransmissions can be degraded by the presence of structural obstacles(e.g., walls, floors, concrete, multiple stories, etc.), largeappliances (e.g., refrigerator, oven, furnace, etc.), human traffic,conflicting devices (e.g., wireless phones, microwave ovens, neighboringnetworks, X10 cameras, etc.), as well as by the physical distancebetween the access point and the mobile terminal or other device. By wayof example, an IEEE 802.11b compliant wireless transceiver may have aspecified data rate of 11.0 megabits per second (Mbps), but the presenceof walls in the transmission path can cause the effective data rate todrop to about 1.0 Mbps or less. Degradation of the video signal can alsolead to repeated transmission re-tries, causing the video image toappear choppy. These practical limitations make present-day wirelesstechnologies one of the most unreliable of all the networking optionsavailable for home media networks.

One proposed solution to this problem is to increase the number ofaccess points in the home, with the various access points beinginterconnected by a high-speed cable wire. The drawback of thisapproach, however, is that it requires that cable wires be routedthrough the interior of the structure.

An alternative solution is to utilize wireless repeaters to extendcoverage of the network throughout the building. For example, D-LinkSystems, Inc., of Irvine, Calif. manufactures a 2.4 GHz wireless productthat can be configured to perform either as a wireless access point, asa point-to-point bridge with another access point, as apoint-to-multi-point Wireless bridge, as a wireless client, or as awireless repeater. As a wireless repeater, the product functions toretransmit packets received from a primary access point. But the problemwith these types of wireless repeaters is that they retransmit at thesame frequency as the primary access point device. Consequently, becausethe primary access point and repeaters share the same channel, thebandwidth of the network is effectively reduced for each repeaterinstalled. For example, if a data packet needs to be repeated (i.e.,retransmitted) three times in the same channel, each packet must waituntil the previous packet has been repeated which means that theresulting bandwidth loss is 67%. So if the initial video transmissionstarts out at, say, 21 Mbps, the effective payload data rate at thereceiver end is diminished to about 7 Mbps. Naturally, with morerepeaters, more data hops are required, so the bandwidth loss becomesworse. This approach basically trades-off bandwidth for signalrange—extending the range of the wireless network, but sacrificingvaluable bandwidth in the process.

Still another attempted solution to the problem of wireless transmissionof video data is to lower the bandwidth of the video through datacompression. This technique involves compressing the video data prior totransmission, then decompressing the data after it has been received.The main drawback with compression/decompression techniques is that theytend to compromise the quality of the video image, which is unacceptableto most viewers. This approach also suffers from the problem of lostconnections during transmission.

In view of the aforementioned shortcomings, there exists a strong needfor a highly reliable wireless network (e.g., on a par with coaxialcable) that provides very high data rates (e.g., 30 Mbps) throughout thefull coverage range of a home or building.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood more fully from the detaileddescription that follows and from the accompanying drawings, whichhowever, should not be taken to limit the invention to the specificembodiments shown, but are for explanation and understanding only.

FIG. 1 is a conceptual diagram of a wireless network according to oneembodiment of the present invention.

FIGS. 2A & 2B illustrate propagation characteristics for access pointsoperating in the 2.4 GHz and 5 GHz frequency bands.

FIG. 3 is an example of wireless signal repeating in accordance with oneembodiment of the present invention.

FIG. 4 is a chart illustrating pipelined data packet flow from source todestination in accordance with one embodiment of the present invention.

FIG. 5 is an example showing limitless data transmission range extensionin accordance with another embodiment of the present invention.

FIG. 6 is an example of wireless signal repeating for 2.4 GHz trafficutilizing a 5 GHz repeater backbone in accordance with anotherembodiment of the present invention.

FIG. 7 is a chart illustrating pipelined data packet flow from source todestination in accordance with the embodiment of FIG. 6.

FIG. 8 is an example of wireless signal repeating for 2.4 GHz trafficutilizing a 5 GHz repeater backbone, with the source and destination onthe same channel in accordance with yet another embodiment of thepresent invention.

FIG. 9 is a chart illustrating pipelined data packet flow from source todestination in accordance with the embodiment of FIG. 8.

FIG. 10 is a perspective view of a wireless repeater in accordance withone embodiment of the present invention.

FIG. 11 is a circuit block diagram of the internal architecture of thewireless repeater shown in FIG. 10.

FIG. 12 illustrates three repeaters configured in a wireless networkaccording to one embodiment of the present invention.

FIG. 13 is a diagram that shows the unlimited range at full bandwidthrange of one embodiment of the present invention.

FIGS. 14A & 14B show a plan view and a side elevation view,respectively, of a floor plan for a building installed with a wirelessnetwork according to one embodiment of the present invention.

FIG. 14C illustrates the repeater topology for the first floor shown inFIGS. 14A & 14B.

FIGS. 15A & 15B show plan and side elevation views, respectively, of thewireless network of FIGS. 14A & 14B, but with a disturbance.

FIGS. 16A & 16B illustrate the network of FIGS. 15A and 15B afterreconfiguration to overcome the disturbance.

FIGS. 17A & 17B illustrate another example of channel conflict in awireless network implemented according to one embodiment of the presentinvention.

FIGS. 18A & 18B illustrate the network of FIGS. 17A and 17B afterchannel reconfiguration.

FIG. 19 is a floor plan showing two simultaneous wireless networksoperating in a building according to one embodiment of the presentinvention.

FIG. 20 shows a wireless network according to another embodiment of thepresent invention.

FIG. 21 is a circuit block diagram of the basic architecture of a DBStuner according to one embodiment of the present invention.

FIG. 22 is a circuit block diagram of the basic architecture of a cabletelevision tuner in accordance with one embodiment of the presentinvention.

FIG. 23 is a circuit block diagram of the basic architecture of awireless receiver in accordance with one embodiment of the presentinvention.

DETAILED DESCRIPTION

The present invention is a self-configuring, adaptive wireless localarea network (WLAN) that utilizes cellular techniques to extend therange of transmission without degrading bandwidth. The wireless networkof the present invention is thus ideally suited for transmitting videoprograms (e.g., digitally-encoded video broadcast services, pay-per-viewtelevision, on-demand video services, etc.) throughout a house or otherbuilding, thereby creating a “media-live” environment.

In the following description numerous specific details are set forth,such as frequencies, circuits, configurations, etc., in order to providea thorough understanding of the present invention. However, personshaving ordinary skill in the communication arts will appreciate thatthese specific details may not be needed to practice the presentinvention. It should also be understood that the basic architecture andconcepts disclosed can be extended to a variety of differentimplementations and applications. Therefore, the following descriptionshould not be considered as limiting the scope of the invention.

With reference to FIG. 1, a wireless home media network 10 according toone embodiment of the present invention comprises a source video accesspoint 11 coupled to a broadband connection. By way of example, thebroadband connection may provide video content from a Direct BroadcastSatellite (DBS) or digital cable service provider. Additional wirelessaccess points (simply referred to as “access points” or “repeaters” inthe context of the present application) may be physically located in adistributed manner throughout the home or building to provideconnectivity among a variety of home media devices configured forwireless communications. As shown in FIG. 1, these home media devicesmay include a laptop personal computer 12, DVD player 13, wireless-readytelevision 14, and wireless-linked receiver 15 coupled to either astandard definition or high-definition television (SDTV/HDTV) 16. Othertypes of devices, such as personal digital assistants (PDAs), may alsobe coupled to network 10 for receiving and/or transmitting data.Practitioners in the art will appreciate that many client media devicessuch as personal computers, televisions, PDAs, etc., have the capabilityof detecting the operating frequency of the access point within aparticular micro-cellular transmission range.

Commands for one or more of these home media devices may be generatedusing a remote control unit 17, either through infrared (IR) or radiofrequency (RF) signals. In one embodiment, wireless network 10 providesreliable, full home coverage at throughputs supporting multiplesimultaneous video streams, e.g., two HDTV streams at approximately 30Mbps; eight SDTV streams at about 16 Mbps.

According to the present invention a plurality of access points isutilized in a wireless network to provide relatively short transmissionranges that preserve bandwidth and achieve high reliability. Thewireless network of the present invention implements a three-dimensional(“3-D”) topology in which communications between an access point andmobile terminals or client media devices in a particular region occur ata frequency which is different than the communication frequency of aneighboring region. In specific embodiments, the 2.4 GHz and 5 GHzfrequency bands are utilized for wireless transmissions. In the UnitedStates, for instance, the 2.4 GHz band provides three non-overlappingchannels, whereas the 5 GHz band provides twelve non-overlappingchannels for simultaneous transmission traffic. The wireless network ofthe present invention achieves full range coverage in the home withoutbandwidth loss by utilizing a different channel for each data packethop. This feature allows repeater data packets to overlap in time, asdiscussed in more detail below.

FIG. 2A is a diagram illustrating the two-dimensional propagationcharacteristics through open air associated with an access point 20operating in the 2.4 GHz band and transmitting on a particular channel,i.e., channel 1. Inner circle 21 represents the range of maximumbandwidth, and outer circle 22 represents the range at which the signalfrom access point 20 ceases to interfere with other signals in the samechannel. FIG. 2B shows an access point 30 operating in the 5 GHz bandwith maximum bandwidth and interference ranges represented by circles 31and 32, respectively. As can be seen, both access points 20 and 30 havea relatively short range at maximum bandwidth, but have a fairly wideinterfering signal range. Notably, access point 30 has a shorterinterference range than access point 20.

FIG. 3 is an example of wireless signal repeating in accordance with oneembodiment of the present invention. In the embodiment of FIG. 3, eachof the access points 20 a-20 c transmits on a different channel. Forinstance, access point 20 a is shown operating on channel #1 in the 2.4GHz band; access point 20 b operates on channel #6; and access point 20c operates on channel #11 in the same band. The inner circles 21 a-21 ceach denotes the ranges of maximum bandwidth associated with accesspoints 20 a-20 c, respectively. (The outer circles 22 a-22 c denotes thesame-channel interference signal range associated with access points 20a-20 c, respectively.) As can be seen, each of the access points isadvantageously located at a distance within the maximum bandwidth rangeof its nearest neighboring access point. Similarly, the destinationmedia device 25 is disposed within the maximum bandwidth range of itsnearest access point 20 c.

In the example of FIG. 3, access points 20 b and 20 c function as signalrepeaters to facilitate transmission of data from source access point 20a to destination device 25. To prevent loss of bandwidth duringtransmission, each of the access points 20 a-20 c repeats transmissionof data packets on a different frequency channel than any of itsneighboring access points within signal interference range. Accesspoints located beyond the interference range of a channel may reuse thatsame channel. In this case, a source data packet 1 is transmitted byaccess point 20 a on channel #1. Access point 20 b repeats transmissionof this data packet on channel #6. Access point 20 c again repeatstransmission of data packet 1; this time on channel #11. Destinationmedia device 25 receives data packet 1 from access point 20 c on channel#11.

After the transmission of data packet 1, access point 20 a mayimmediately transmit a second source data packet (“packet 2”), followedby a third source data packet, a fourth data packet, and so on. Each ofthese data packets are repeated across the network in a pipeline mannerby access points 20 b and 20 c, as shown in FIG. 4. Pipelining of datapackets across channels facilitates transmission of video data withoutloss of bandwidth. The wireless network of the present invention has nolimitation on how far the transmission of data can extend, as long asthere are a sufficient number of channels available.

In the 2.4 GHz band, three channels allows for three hops in anydirection (including the initial transmission from the source) inthree-dimensional space at maximum bandwidth. Since each hop normallycan extend about 50 feet at maximum bandwidth, three hops on threedifferent channels (one source plus two repeaters) can cover a distanceof about 150 feet from source to destination. In the license-free 5 GHzband (e.g., 5725 MHz to 5850 MHz), there are currently twelve channelswith upwards of 54 Mbps of bandwidth available on each channel in goodtransmission conditions. As with the 2.4 GHz band, each hop in the 5 GHzband will typically extend about 50 feet at maximum bandwidth, but thelarge number of channels permits hops to extend indefinitely. That is,in a wireless network operating in the 5 GHz band according to thepresent invention, repeaters extend far enough for channel reuse. Thismeans that hops can extend the range of transmission from source todestination without limitation.

FIG. 5 is an example showing a network configuration in which each hopextends about 50 feet, so that ten hops cover about 500 feet. In thisexample, after ten hops, any channel beyond its interference range maybe reused. Note that the smaller inner circles representing the range ofmaximum bandwidth around the access points that operate on the samechannel frequency (e.g., channel #1) are separated by a considerabledistance (˜400 feet). Note that each access point is shown spaced-apartfrom its nearest neighboring access point by a distance less than themaximum bandwidth range (i.e., small circle) of its nearest neighbor. Atthe same time, any two access points transmitting on the same channelare shown separated from each by a distance greater than theinterference signal range. Access points that re-use the same channelare separated by a distance greater than their respective signalinterference ranges. The large spatial separation between access pointsusing the same frequency channel means that transmission problems due tochannel interference between access points operating on the same channelare virtually nonexistent in the wireless network of the presentinvention.

In addition to neighboring access points operating on differentchannels, different frequency bands may also be used during datatransmission across the wireless network of the present invention. In analternative embodiment, for instance, 5 GHz repeaters may be utilized toform an arbitrary length backbone for 2.4 GHz data traffic. Thissituation is illustrated in the example of FIGS. 6 & 7, which showssource access point 40 a transmitting data packets to a 2.4 GHzdestination 55 using 5 GHz repeaters 40 b & 40 c. Note that source point40 a and repeater 40 d (transmitting to destination device 55) bothoperate in the 2.4 GHz band, but utilize different channels, i.e.,channels #6 and #11, respectively, to prevent bandwidth loss.

Another possibility is to use a 5 GHz device at the destination and a2.4 GHz access point at the source or vice-versa. As long as the networkis configured for communications with source-to-destination frequencyband transitions of 2.4 GHz to 5 GHz, or 5 GHz to 2.4 GHz, or 2.4 GHz to2.4 GHz on different channels (all utilizing 5 GHz for repeatersin-between), the network can provide an arbitrary length backbone for2.4 gigahertz traffic, despite the fact there are only three 2.4 GHzchannels available. In other words, the wireless network of the presentinvention is not limited to data transmissions confined to a singlefrequency band.

It is also possible to configure a wireless network in accordance withthe present invention where the source and destination devices bothoperate at 2.4 GHz using the same channel. Such an embodiment is shownin the conceptual diagram of FIG. 8 and the associated transmissionchart of FIG. 9, wherein source access point 40 a and repeater 40 dassociated with destination media device 55 both operate in the 2.4 GHzband on channel #6. Repeaters 40 b and 40 c operate in the 5 GHz band onchannel #1 and #2, respectively. Although this particular embodiment hasa penalty of 50% bandwidth loss, the network still may be extended toarbitrary length with no additional bandwidth loss, regardless of thetotal distance covered. It is appreciated that the 50% bandwidth loss inthis embodiment results from the need to stagger the data packettransmissions, as shown in the chart of FIG. 9, to avoid interferencebetween the packet transmission by access point 40 a and the packettransmission by repeater 40 d.

With reference now to FIG. 10, there is shown a perspective view of awireless repeater unit 60 configured for installation in an ordinaryelectrical outlet in accordance with one embodiment of the presentinvention. FIG. 11 is a circuit block diagram of the internalarchitecture of repeater unit 60. Repeater unit 60 comprises atransformer/power supply 61 that provides supply voltages to the variousinternal electronic components, which include a CPU 62, a RAM 63, aFlash ROM 64, and input/output application specific integrated circuitry(I/O ASIC) 66, each of which is shown coupled to a system bus 65. Alsocoupled to system bus 65 are a plurality of transceivers, which, in thisparticular embodiment, include a 5 GHz “upstream” transceiver 74, a 5GHz “downstream” transceiver 75, and a 2.4 GHz transceiver 76. Each oftransceivers 74-76 is coupled to an antenna 77. Additional transceiversoperating at different frequencies may be included in repeater unit 60.

CPU 62 controls the re-transmission of the received data packets,utilizing RAM 63 for both program execution, and for buffering of thepackets as they are received from the upstream side, i.e., nearest thesource, before they are sent out to the downstream side, i.e., towardthe destination. Flash ROM 64 may be used to hold software andencryption key information associated with secure transmissions, forexample, to insure that the network users are authorized users ofsatellite or cable subscriber services.

In the embodiment of FIG. 11, a 1394 connector interface 70 provides aFirewire® port (coupled through a 1394 PHY physical interface 73) to I/OASIC 66. Also coupled to I/O ASIC 66 is a pushbutton switch 69 and anLED indicator panel 71. Pushbutton switch 69 may be utilized inconjunction with interface 70 to authenticate repeater unit 60 for usein the network after the wireless receiver or source access point hasbeen initially installed. These aspects of the present invention will bedescribed in more detail below.

By way of example, FIG. 10 further shows that the upstream repeater inthe network comprises a wireless transceiver that operates in compliancewith IEEE specification 802.11a to run with an effective throughput of36 Mbps utilizing large packets of approximately 2500 bytes each.Persons of skill in the art will understand that IEEE 802.11a is astandard that permits use at more than one channel at a time. On thedownstream side is another repeater that comprises a 5 GHz band, 802.11awireless transceiver that operates on a different frequency channel. Itshould be understood that the present invention is not limited to theseparticular transceiver types or frequency bands. Other embodiments mayutilize other types of transceivers; for instance, transceivers thatoperate in compliance with specifications that are compatible with IEEEspecification 802.11a, 802.11b, or 802.11g, or which otherwise providefor wireless transmissions at high-bandwidths. For the purposes of thepresent application, IEEE specification 802.11a, 802.11b, 802.11g, andIndustrial, Scientific, and Medical (ISM) band networking protocols aredenoted as “802.11x”.

Other non-ISM bands wireless network protocols could be utilized aswell. For example, instead of utilizing 802.11a transceivers in the 5GHz band, the network of the present invention could be implementedusing transceivers compatible with HIPERLAN2, which runs with aneffective throughput of about 42 Mbps.

Transmissions between repeater unit 60 and client wireless media deviceslocated nearby are shown at the top of FIG. 10. In this example, a 36Mbps effective throughput link is provided through an 802.11g 2.4 GHztransceiver that may be used to connect to any local devices operatingin the 2.4 GHz band. An 802.11a compatible transceiver may also beutilized to connect to local media devices operating in the 5 GHz band.In a network configured with multiple wireless repeaters, each wirelessrepeater may provide wireless communications to one or more localdevices. FIG. 12, for example, illustrates three repeaters 60 a-60 cconfigured in a network wherein each repeater may provide acommunication link to nearby wireless devices, such as laptop computersor wireless televisions, etc. Thus, by properly distributing repeaterunits throughout a home or office building, media content may bedelivered at high bandwidths to client devices located anywhere in thehome or office environment.

Repeater units 60 may be installed in the wireless network of thepresent invention after the source access point (e.g., source videoreceiver) has been made operational. In one embodiment, a new repeaterunit 60 is first connected to the source access point or an existingrepeater (one that is already plugged into an outlet and coupled to thewireless network) using a Firewire cable. The Firewire cable isconnected between the existing repeater or source access point and thenew repeater. Power is provided over the Firewire cable from theexisting repeater or access point to the new repeater to activate theinternal circuitry of the new repeater, so that encryption keyinformation may be exchanged to allow the new repeater to securelyconnect to the network. Execution of program instructions for theexchange of encryption information may be initiated by the personperforming the installation pressing pushbutton switch 69, located onthe front side of repeater unit 60 in FIG. 10.

After the exchange of encryption information has completed, the Firewirecable between the two devices may be disconnected. The repeater unitwith the newly activated encryption key may then be plugged into anelectrical outlet in any location of the home or building where the userwants the network to extend.

Once repeater unit 60 is plugged in, it immediately outputs anindication of received signal strength on LED indicator panel 71. LEDindicator panel 71 provides an indication of transmission signalstrength to the upstream receiver, and may be advantageously used tolocate repeater unit 60 to extend the network in a home or building. If,for example, the LED output indicates a strong signal, the installer maywish to remove the repeater unit from its present wall outlet locationto a location farther away from the nearest existing repeater or accesspoint. If, upon moving to a new location, LED indicator panel 71 outputsa “weak” or a “no signal” reading, this means that the new repeater istoo far away from existing connection points of the network. In eithercase, the installer should move the repeater unit back closer to anexisting repeater or access point until a “good” or “strong” signalstrength is indicated.

Another option is to provide an audio indication of the transmissionsignal quality, instead of a visual indication.

Once the source access point (e.g., video receiver) detects the presencea newly-activated repeater unit, it automatically self-configures thecellular repeater wireless network. This aspect of the present inventionwill be explained in greater detail below.

The example network shown in FIG. 13 illustrates the unlimited range atfull bandwidth feature of one embodiment of the present invention. InFIG. 13, a video access point 80 is shown running at 36 Mbps to transmitinformation and video data downstream to a destination television 81containing a wireless receiver located in a distant room. The video datamay originate from a data service connection, such as a Direct BroadcastSatellite (DBS), DSL, or cable television (CATV), provided to accesspoint 80. Repeaters 60 a and 60 b function as intermediary access pointsto distribute the video content to client media devices in their localvicinity, and to repeat downstream data packets received on the upstreamside. As can be seen, each repeater transmits at 36 Mbps so theeffective throughput received at destination television 81 remains at 36Mbps, i.e., without bandwidth loss.

FIGS. 14A & 14B show a plan view and a side elevation view,respectively, of a floor plan of a building 84 installed with fourseparate, secure wireless networks according to one embodiment of thepresent invention. FIG. 14C illustrates the repeater topology for thenetwork installed on the first floor plan shown in FIGS. 14A & 14B.Source access points (e.g., video tuners or data routers) in building 84are denoted by circles, with the number inside the circle designatingthe frequency channel used. Additional access points (i.e., repeaters)are denoted by squares, with the number inside the square similarlydesignating the channel used for signal transmissions. In the example ofFIGS. 14A-14C, four source access points 85-88 are each shown connectedto a broadband network (e.g., cable, DSL, etc.), with each source accesspoints functioning as a broadband tuner/router. Thus, four separatewireless networks are shown installed on separate floors of building 84.

With reference to the first floor plan shown in FIGS. 14A-14C, accesspoint 85 transmits video data packets on channel #1 to repeaters 91 and92, which then both repeat the received data packets on channel #2.Repeaters 93 and 94 (both on channel #3) are shown branching off ofrepeater 91. Repeater 95 (channel #4) is coupled to the network throughrepeater 93. Repeater 96 (channel #4) branches off of repeater 94;repeater 97 (channel #1) branches off of repeater 96; and repeater 98(channel #2) branches off of repeater 97 to complete the first floortopology. Note that repeater 97 is able to reuse channel #1 since it islocated a relatively far distance from source access point 85, whichuses the same channel. Additionally, the side elevation view of FIG. 14Bshows there are no devices on the second floor network above repeater 97that use channel #1. For the same reasons, repeater 98 is able to reusechannel #2.

It is appreciated that access point 85 only needs one transceiver tocreate the repeating wireless network shown in FIGS. 14A-14C. Theinternal transceiver of access point 85 transmits on channel #1, whichtransmission is then received by the upstream transceivers of repeaters91 and 92. Repeater 91 transmits using its downstream transceiver onchannel #2, which is then picked up by the two upstream transceivers ofrepeaters 93 and 94, each of which, in turn, transmits on theirdownstream transceiver to repeaters 95 and 96, respectively, and so on.Note that in this example, access point 98 only transmits downstream todestination media devices, not to another access point. That is, accesspoint 98 does not function as a repeater; rather, access point 98 simplycommunicates with the destination media devices in its local area.

Practitioners in the communications arts will also understood thatnearby access points transmitting on the same channel in the first floornetwork shown in FIGS. 14A-14C (e.g., repeaters 91 & 92) do notinterfere with one another. The reason why is because a given message ordata packet is only transmitted down one path of the topology tree at atime. Moreover, according to the embodiment of FIGS. 14A-14C, eachaccess point in the topology tree does not need an arbitrary number oftransceivers to repeat data messages across the network; an upstreamtransceiver and a downstream transceiver suffices. As describedpreviously, an additional 2.4 GHz band transceiver may be included, forexample, to provide communications with 802.11b or 802.11g compatibledevices. It should be understood, however, that there is no specificlimit on the number or type of transceivers incorporated in the accesspoints or repeaters utilized in the wireless network of the presentinvention.

The self-configuring feature of the present invention is also apparentwith reference to FIGS. 14A-14C. According to one embodiment of thepresent invention, a processor in the source access point executes aprogram or algorithm that determines an optimal set of frequencychannels allocated for use by each access point or repeater. An optimalset of channels is one that does not include over-lapping channels andavoids channels used by other interfering devices in the same locality.An optimal channel configuration may also be selected that maximizeschannel re-use. Further, once a set of the channels has been chosen foruse by the access points, modulated power can be reduced to the minimumneeded to achieve maximum bandwidth across each link so as to reducesignal reflections. As discussed below, the wireless network of thepresent invention may also adapt to changes to the network byreconfiguring the channel assignments, such as when new repeaters areadded, existing ones removed, or when the network experiencesdisturbances caused by other interfering devices (e.g., from aneighboring network).

Note that in FIGS. 14A-14C, the first floor wireless network has beenconfigured such that the channels used by each of the access points donot interfere with other devices located on other floors of building 84.The side elevation view of FIG. 14B shows that interference sources arepresent in the upper stories of building 84 above the wireless networkcreated by source access point 85. To avoid interference with thedevices using channels #5-#10 on the second through fourth floors, thefirst floor network has configured itself to use channel #1, #2, #3 and#4.

The circuitry for controlling the self-configuration process may eitherbe centralized in the source access point or distributed throughout theaccess points comprising the wireless network. In either case, thesystem may proceed through a process of iteration, wherein everypossible combination of channels allocated to the access points may betried in order to find an optimal combination of frequency channels. Inone embodiment, the network hops through the frequency channelsautomatically so that an optimal combination of frequencies may bedetermined. Within a matter of seconds, the network may completeiterating through all permutations of channels to identify whichcombination of frequencies produces the best result. One example of abest result is the highest average bandwidth from source to eachdestination. Another best result may be defined as one which optimizesbandwidth to certain destination devices. For instance, if a particulardestination device (e.g., a video receiver) requires higher bandwidththan other destination devices, then allocation of channels may beoptimized to provide higher bandwidth in the network path to theparticular destination device at the expense of lower bandwidth to otherdevices.

The system of the present invention also functions to keep modulatedpower in the network to a minimum. It may be necessary in someinstances, for example when transmitting through many walls to a maximumrange, to use a lot of power. In other instances, a repeater is locatednearby and there may be few walls to transmit through, so lesstransmission power is required. When the network initially turns on, theaccess points may transmit at maximum power to establish a maximum rangeof communication. However, once communications have been establishedwith all of the repeaters in the network, the power output may bereduced to a level that provides adequate signal transmissioncharacteristics (i.e., a threshold signal strength), but no more. Inother words, the network may throttle power output, keeping it only ashigh as it needs to be to create a strong signal to the next repeater.One benefit of such an operation is that it reduces signal reflectionsthat may interfere with the reception quality. Another benefit is lesspower consumption.

Another benefit of the power management feature of the present inventionis that by having a given channel prorogate less distance, you createthe opportunity to reuse that channel in the network at an earlier pointin the topology than if transmissions were at maximum power.

According to one embodiment, the wireless network of the presentinvention automatically detects channel conflicts that arise, and adaptsthe network to the conflict by reconfiguring itself to avoid theconflict. That is, the access points monitor the signal quality of thewireless transmissions on a continual basis. Any disturbance or conflictthat causes signal transmissions to fall below an acceptable qualitylevel may trigger an adaptive reconfiguration process.

By way of example, FIGS. 15A and 15B show plan and side elevation views,respectively, of the wireless network previously shown in FIGS. 14A &14B, but with a disturbance generated by the activation of a cordlessphone (shown by square 101 operating on channel #2) in building 84. Asshown, the interference caused by cordless phone 101 is within the rangeof repeaters 91 and 92, thereby affecting the transmissions of thoserepeaters. In accordance with one aspect of the present invention, thenetwork automatically detects the channel conflict and reconfiguresitself to overcome the interference.

FIGS. 16A and 16B illustrate the network of FIGS. 15A and 15B afterreconfiguration to overcome the channel conflict caused by cordlessphone 101. As can be readily seen, building 84 is populated with manyexisting channels in use. Because of the channel usage in the upperstories, the network cannot simply swap out the channels used byrepeaters 91 & 92 with a different one. Instead, in this example, thewireless network of the present invention replaces channel #1 of sourceaccess point 85 with channel #5. That permits channel #1 to replacechannel #2 in both repeaters 91 & 92. In addition, because the channel#1 usage by repeaters 91 & 92 would be too close to the channel #1 usageby repeater 97 (see FIGS. 15A & 15B), the wireless network also replaceschannel #1 of repeater 97 with channel #8. Note that channel #8 can beused for repeater 97 because its only other use in building 84 is on thefourth floor at the opposite end of the structure. Repeater 98 is alsoshown reconfigured to use channel #1 instead of channel #2.

The adaptation process discussed above may be performed in a similarmanner to the self-configuration process previously described. That is,all of the different possible combinations of channels may be trieduntil the network identifies an optimal combination that works toovercome the channel conflict without creating any new conflicts. Theadaptation process may rely upon an algorithm that does not attempt tochange or move channels which have already been established. In theexample of FIGS. 16A and 16B, for instance, channel #3, used byrepeaters 93 & 94, and channel #4, used by repeaters 95 & 96, are leftin place. In other words, regardless of the origin of a channelconflict, the network of the present invention adapts to the disturbanceby reconfiguring itself to optimize performance.

In the unlikely event that a channel conflict is truly unavoidable,i.e., no combination of channels exists that would allow the network toextend from the source to any destination without conflict (as couldoccur in a situation where there is heavy use of channels by neighboringnetworks) the wireless network of the present invention can reducebandwidth and still maintain connectivity. Such a scenario is depictedin FIGS. 17A & 17B and FIGS. 18A & 18B.

FIGS. 17A & 17B illustrate the conflict previously shown in FIGS. 15A &15B, wherein a cordless phone 101 is activated, except with anadditional channel conflict created by a wireless camera 102 operatingon channel #5. Here, due to the additional conflict caused by camera102, there is no combination of channel allocations that might allow thenetwork to reach from any source to any destination without conflict. Insuch a situation, the network has adapted by reusing the same channel inconsecutive branches of the repeater topology, as shown in FIGS. 18A &18B. FIGS. 18A & 18B show the reconfigured wireless network withrepeaters 91 and 92 using channel #3. Because repeaters 93 and 94 alsooperate on channel #3 the bandwidth of the network is reduced by 50%.The benefit of the channel switching, however, is still preservedthroughout the remainder of the network. Unlike a conventional repeatingnetwork that continues to lose bandwidth through each leg or repeatingsegment of the network, in the special situation exemplified in FIGS.18A & 18B there is the only place in the network where bandwidth islost. Moreover, the total bandwidth loss stays at 50%; that is,bandwidth is not continually reduced by each successive repeatingsegment of the network.

In yet another embodiment of the present invention, simultaneouswireless networks may be created to run at the same time. Simultaneouswireless networks may be desirable in certain applications, say, wherethere are three HDTV sets each operating at 15 Mbps. If the backbone ofthe primary network operates at 36 Mbps, the available bandwidth isinsufficient to accommodate all three screens. The solution provided bythe present invention is to install a second video tuner (i.e., a secondsource access point) and double up the number of repeaters through eachbranch of the rest of the topology.

FIG. 19 is a floor plan showing two simultaneous wireless networksoperating in a building 84 to increase bandwidth. Such an arrangement isideally suited to support multiple HDTV video streams. In the example ofFIG. 19 access points 110 and 120 each comprise a wireless video tuneror router with a broadband connection. Access point 110 is shownoperating on channel #1 and access point 120 is shown operating onchannel #5. In this case, separate paths are created to the upper leftand lower left sections of the floor plan. The path from access point110 includes repeaters 111, 112 and 113 on respective channels #2, #3and #4. Meanwhile, the path from access point 120 is implemented usingrepeaters 121, 122, 123, 124 and 125 on channels #6, #7, #8, #9 and #10,respectively.

It should be understood that as long as there are a sufficient number ofchannels available, bandwidth can be increased arbitrarily in thearrangement of FIG. 19. In other words, three, four, or moresimultaneously running wireless networks may be implemented in a home oroffice environment to arbitrarily increase bandwidth to meet increasingdata rate demands. If an adequate number of channels is available (e.g.,allowing extension of the network across a sufficient distance forchannel reuse), there is no limitation on the bandwidth that can beachieved in accordance with the present invention.

The security features provided by the wireless network of the presentinvention are discussed in conjunction with the example of FIG. 20. FIG.20 shows a wireless network according to one embodiment of the presentinvention which includes a tuner 130 coupled to receive real-timestreaming media from a source, such as DBS or CATV. Tuner 130 transmitsthe media content provided by the source, possibly through one or morerepeaters, to a destination device, which in this example, comprises awireless receiver 133, connected to a standard definition television134. The media content provided by the source is, of course, encrypted.Only authorized users or subscribers are permitted access to the mediacontent. Tuner 130 typically receives the media data from the cable orsatellite provider in a digitally encrypted form. This encryption ismaintained through the wireless network to SDTV 134. Wireless receiver133 is a trusted device; that is, it is secured during installation byexchange of encryption key information. Consequently, receiver 133 isable to decrypt the media content when it arrives across the networkfrom tuner 130. Thus, data security is preserved across the entire spanof the wireless network, potentially over many repeater hops, so thatinterlopers or unscrupulous hackers are prevented from gainingunauthorized use of the wireless local area network.

In addition to encrypted data, the wireless network of the presentinvention may also transmit presentation layer data and information,such as overlay graphics and remote controls for interactiveexperiences. To put it another way, the network may also carryinformation both upstream and downstream.

Practitioners in the art will further appreciate that tuner 130 may alsodigitize analog video, decode it, and compress the received source dataprior to transmission across the wireless network, in addition toreceiving compressed digital video. In the case where compressed videois transmitted by tuner 130, receiver 133 decompresses the data as it isreceived. Alternatively, decompression circuitry may be incorporatedinto television 134 (or into an add-on box) that performs the same task.Receiver 133, or a wireless-enabled television 134, may identify itselfas a device that requires high bandwidth to the upstream wirelessrepeaters 60 and tuner 130. When the network re-configures itself toavoid an interference source, it may take this requirement intoconsideration during channel allocation to optimize bandwidth in thenetwork path from tuner 130 to receiver 133 or wireless-enabledtelevision 134.

In an alternative embodiment, tuner 130 decrypts the real-time mediastream as it is received from the satellite or cable service provider,and then re-encrypts that same data using a different encryption schemethat is appropriate for the wireless local area network. Thus, in thisalternative embodiment, only devices properly enabled by the network areauthorized to play media content received via that network. Note thatbecause the wireless network in this embodiment of the present inventionis a single or uni-cast signal, it can only be received by a properlyenabled receiver that is authorized with appropriate encryption keyinformation. In other words, the media content transmitted across thenetwork from source to destination is not simply available to anyone whohappens to have a receiver.

Still another possibility is for the cable or satellite company to grantan entitlement to tuner 130 that allows a certain limited number ofstreams (e.g., three or four) to be transmitted in a particularhousehold or office environment, regardless of the number of mediaclient devices that actually receive the media content. This is simplyanother way to restrict distribution of the media content.

In yet another alternate embodiment, tuner 130 receives video datapackets from a DBS or digital cable TV source and buffers the packets inits internal RAM (see FIG. 21). The video data packets may then begrouped together into a larger packet. For example, an MPEG-2transmission may have 188-byte packets, which would result in lowefficiency over a 802.11x transport. By grouping these relatively smallpackets into a larger packets (e.g., twelve 188-byte packets groupedtogether to form a 2.256-Kbyte packet), better 802.11x efficiency can beachieved. Many conventional 802.11x networks incur a high probability ofa transmission error when transmitting such large packets over longdistances. The occurrence of such an error, of course, requiresre-transmission of the packet, with the same risk of another errorhappening during the re-transmission. By utilizing repeaters separatedby relatively short distances (i.e., within the maximum bandwidth rangeof the repeaters), the transmission error rate is dramatically reduced(e.g., <10⁻⁶) as compared to conventional wireless networks. Thus,because larger packets (e.g., 500 bytes or greater) may be utilized, thewireless network of the present invention is capable of achieving a higheffective throughput (e.g., as much as 36 Mbps or greater) at low errorrates. By way of example, and not limitation, one embodiment of thepresent invention is capable of achieving approximately 32 Mbpseffective throughput, transmitting 2.256-Kbyte packets across an 802.11xnetwork of arbitrary length with a bit error rate of about 10⁻⁷ or less.

Another feature of the present invention is the ability toserendipitously provide connectivity to any user who happens to bewithin the range of the wireless network. If, for instance, a wirelessrepeater or access point is mounted near a window or on the rooftop of abuilding, the outdoor range of the wireless network may be extended to anearby park or other buildings (e.g., a café or coffeehouse). A user whohas a laptop computer configured with an existing wireless transmitterand receiver, and who happens to be within the range of the wirelessnetwork, could connect to the Internet; view a video program; listen toan audio program; or store media content on its disk drive for retrievaland play at a later time (assuming proper entitlements). In other words,the present invention provides ever greater mobility by allowingportable computer users to take media content with them.

Media content may also be downloaded from the wireless network forarchival storage on a wireless disk server.

Those of ordinary skill in the art will further appreciate that thewireless network of the present invention is client device independent.It does not matter to the network what type of device is at thedestination end receiving the transmitted media content. Video andgraphics content carried on the WLAN of the present invention can playon multiple types of television, computers (e.g., Macintosh® or PC),different MP3 players, PDAs, digital cameras, etc. By way of example,any PC or Mac equipped with a 2.4 GHz band wireless card can detect thepresence of the wireless network. Once it has detected the runningwireless network, it may download a driver that contains the necessarysecurity and protocol information for accessing the media content.Readily available software, such as RealPlayer®, QuickTime®, or Windows®MediaPlayer, may be used to play content provided through the network.

With reference now to FIG. 21, a circuit block diagram showing thearchitecture of a DBS tuner according to one embodiment of the presentinvention is shown. Similar to the architecture of the repeater unitshown in FIG. 11, a CPU 144, a RAM 145, a Flash ROM 146, and I/O ASIC147 are coupled to a system bus 150. A 5 GHz band downstream transceiver156 and a 2.4 GHz band transceiver 157, both of which are connected toantenna 160, are also coupled to system bus 150. (An upstreamtransceiver is not needed at the source end.)

Data from the satellite feed is received by a tuner 140 and output todecryption circuitry 141, which may be configured to receive the latestencryption key information from a smart card 142. The decrypted digitalstream output from block 141 is then re-encrypted by encryptioncircuitry 143 prior to being sent over the wireless network. Asdiscussed above, the re-encryption is a type of encryption appropriatefor the wireless network, not one that is locked into the satelliteencryption scheme.

The architectural diagram of FIG. 21 is also shown including connector,indicator, and pushbutton blocks 151-153, as previously described inconjunction with FIG. 11. A power supply unit 159 provides a supplyvoltage to the internal electronic components of the tuner.

FIG. 22 is a circuit block diagram illustrating the basic architectureof a cable television tuner in accordance with one embodiment of thepresent invention. Practitioners in the art will appreciate that thearchitecture of FIG. 22 is somewhat more complicated due to the presenceof both analog and digital signal channels. Elements 161-172 arebasically the same as the corresponding components of the DBS tunerdescribed above.

Tuner 175 receives the cable feed and separates the received signal intoanalog or digital channels, depending on whether the tuner is tuned toan analog or digital cable channel. If it is an analog channel, thevideo content is first decoded by block 177 and then compressed (e.g.,MPEG2 or MPEG4) by circuit block 180 prior to downstream transmission.If it is a digital channel, a QAM demodulator circuit 176 is used todemodulate the received signal prior to decryption by block 178. A pointof deployment (POD) module 179, which includes the decryption keys forthe commercial cable system, is shown coupled to decryption block 178.After decryption, the streaming media content is re-encrypted by block181 before transmission downstream on the wireless network.

FIG. 22 shows a one-way cable system. As is well-known to persons ofordinary skill in the art, a two-way cable system further includes amodulator for communications back up the cable, as, for example, when auser orders a pay-per-view movie.

FIG. 23 is a circuit block diagram illustrating the basic architectureof a wireless receiver in accordance with one embodiment of the presentinvention. Like the repeater, DBS tuner, and cable tuner architecturesdescribed previously, the wireless receiver shown in FIG. 23 includes aCPU 185, a RAM 186, and a Flash ROM 187 coupled to a system bus 188. Apower supply unit 184 provides a supply voltage to each of the circuitelements shown.

A 5 GHz band upstream transceiver 189 is also shown in FIG. 23 coupledto an antenna 190 and to system bus 188. A single transceiver is allthat is required since the receiver of FIG. 23 does not transmitdownstream and it outputs directly to a display device such as atelevision. As described earlier, the 5 GHz band offers the advantage ofmore available channels. Accordingly, I/O ASIC circuitry 192 coupled tobus 188 includes the graphics, audio, decryption, and I/O chips(commercially available from manufacturers such as Broadcom Corporationand ATI Technologies, Inc.) needed to generate the output signals fordriving the display device. Accordingly, in addition to elements 193-195found on the repeater architecture of FIG. 11, I/O ASIC 192 may alsoprovide outputs to a DVI connector 196 (for HDTV), analog audio/video(A/V) outputs 197, an SP/DIF output 198 (an optical signal for surroundsound and digital audio), and an infrared receiver port 199 forreceiving commands from a remote control unit.

It should be understood that elements of the present invention may alsobe provided as a computer program product which may include amachine-readable medium having stored thereon instructions which may beused to program a computer (or other electronic device) to perform aprocess. The machine-readable medium may include, but is not limited to,floppy diskettes, optical disks, CD-ROMs, and magneto-optical disks,ROMs, RAMs, EPROMs, EEPROMs, magnet or optical cards, or other type ofmachine-readable medium suitable for storing electronic instructions.Elements of the present invention may be downloaded as a computerprogram product, wherein the program may be transferred from a remotecomputer (e.g., a server) to a requesting computer (e.g., a client) byway of data signals embodied in a carrier wave or other propagationmedium via a communication link (e.g., a modem or network connection).

Furthermore, although the present invention has been described inconjunction with specific embodiments, numerous modifications andalterations are well within the scope of the present invention.Accordingly, the specification and drawings are to be regarded in anillustrative rather than a restrictive sense.

1. A computer-implemented method of operation for a wireless local areanetwork (WLAN) that includes a repeater topology, the method comprising:detecting a conflict on a channel of a frequency band in a branch of therepeater topology; and adapting the WLAN to the conflict byre-configuring a first repeater in the branch to re-use a certainchannel already in use by a neighboring repeater in the repeatertopology, the first repeater and the neighboring repeater beingphysically obstructed from a line-of-sight view, the first repeaterbeing re-configured to transmit data at a data throughput of at least 11Mbps on the certain channel during even time intervals and receive dataat the data throughput on the certain channel during odd time intervals,the neighboring repeater transmitting during the odd time intervals andreceiving during the even time intervals.
 2. The computer-implementedmethod of claim 1 wherein a next successive repeater in the repeatertopology receives data on the certain channel from the first repeaterand re-transmits the data on a different channel.
 3. Thecomputer-implemented method of claim 1 further comprising monitoringsignal quality of the certain channel during data transmissions.
 4. Thecomputer-implemented method of claim 1 wherein the conflict arises fromoperation of a wireless device not connected to the WLAN.
 5. Thecomputer-implemented method of claim 1 wherein the detecting andadapting steps are performed by at least one processor of the WLAN. 6.The computer-implemented method of claim 1 wherein the detecting andadapting steps are performed by at least one processor of an accesspoint that functions as a data source.
 7. The computer-implementedmethod of claim 1 wherein the frequency band comprises a 5 GHz frequencyband.
 8. The computer-implemented method of claim 1 wherein thefrequency band comprises a 2.4 GHz frequency band.
 9. Acomputer-readable memory encoded with a computer program for configuringa wireless network that includes a repeater topology, when executed, thecomputer program being operable to: detect a conflict on a channel of afrequency band in a branch of the repeater topology operating at a datathroughput of at least 11 Mbps; and adapt the wireless network to theconflict by re-configuring a first repeater in the branch to re-use acertain channel already in use by a neighboring repeater in the repeatertopology, the first repeater and the neighboring repeater beingphysically obstructed from a line-of-sight view, the first repeaterbeing re-configured to transmit data at the data throughput on thecertain channel during even time intervals and receive data at the datathroughput on the certain channel during odd time intervals, theneighboring repeater transmitting during the odd time intervals andreceiving during the even time intervals.
 10. The computer-readablememory of claim 9 wherein a next successive repeater in the repeatertopology receives data on the certain channel from the first repeaterand re-transmits the data on a different channel.
 11. Thecomputer-readable memory of claim 9 wherein the conflict arises fromoperation of a wireless device not connected to the wireless network.12. The computer-implemented method of claim 9 wherein the frequencyband comprises a 5 GHz frequency band.
 13. The computer-implementedmethod of claim 9 wherein the frequency band comprises a 2.4 GHzfrequency band.